Nerve Palsies in Limb Flashcards
When are classic brachial plexus lesions seen?
Downward traction - ex. fall on side of neck and childbirth
C5,6 damage - deltoid and shoulder muscles, brachialis and biceps
What position does C5 and C6 damage result in?
Erb-Duchenne paralysis - porter’s tip
Arm adducted as deltoid not working
Elbow is extended as biceps not working
Forearm pronated and wrist flexed
What damages the upper cords of the brachial plexus?
Upward traction - breech delivery
T1 damage - intrinsic muscles
What is the sign of T1 damage?
Klumpke’s palsy - damage to intrinsic muscles giving claw hand
Describe the axillary nerve
Posterior cord
Wraps around the neck of humerus
Supplies deltoid and teres minor
Supplies skin over lateral arm - regimental badge area
What can cause axillary nerve palsy?
Shoulder dislocation
Fracture surgical neck of humerus
How is axillary nerve tested to see if damaged?
Test regimental badge area - reduced sensation
Leads onto deltoid atrophy - cant actively abduct arm
Describe the radial nerve
Posterior cord
Supplies triceps in arm
Runs in radial groove of humerus as it passes medial to lateral
Supplies BCR, ECRL and ECRB before dividing into posterior (motor) and superior interosseous nerve (sensory)
When do you get radial nerve palsy?
Entrapment
Compression - Saturday night palsy (pressure on nerve for period so zone of reduced circulation)
What are the symptoms of radial nerve palsy?
In axilla - loss of elbow extension, wrist extension and sensory changes to forearm and hand
Arm - loss of wrist extension and sensory loss
Forearm - loss of finger extension (PIN)
Wrist - loss of sensation (SRN)
Describe the median nerve
Medial and lateral cord
Supplies flexors of forearm and LOAF muscles
Supplies sensation to radial 3.5 digits
Describe the carpal tunnel
Floor is carpal bones and roof is flexor retinaculum
Contents - FDS x4, FDP x4, FPL and median nerve
What are the causes of carpal tunnel syndrome/
Developmental
Trauma - distal radius fracture
Swellings - ganglion, fibroma and lipoma
Inflammatory - rheumatoid, gout, TB and amyloid
Metabolic - pregnancy, hypothyroidism and mucoploysaccharidoses
What is the symptoms of carpal tunnel syndrome?
Nocturnal pain and paraesthesia in part or all of median nerve distribution
Wasting of thenar muscles
What is done during examination of carpal tunnel syndrome?
Look - thenar wasting, previous scar and deformity
Feel - sensation
Move - APB power
Special tests - Tinnels (area over tunnel tapped and feel shouting sensations) and Phalens (back of hand together and over time then pain and tingling)
How is carpal tunnel treated?
Night splints
Hypothyroidism treatment
Steroid injection - resolves up to 50%
Ultimately need to divide roof of carpal tunnel at level of wrist and release pressure on median nerve
Describe the ulnar nerve
Medial cord
No branches in arm
Enters forearm between 2 heads of FCU
Supplies medial half of FDP, FCU and all intrinsic muscles in hand bar the LOAF muscles
Sensation to ulnar 1.5 digits
What is cubital tunnel syndrome?
Second most common nerve entrapment
Cubital tunnel between medial epicondyle and olecranon, with fascial bands from FCU roof
What is the symptoms of cubital tunnel syndrome?
Patient has numbness on ulnar side of hand and difficulty with fine tasks
Describe muscle wasting in ulnar nerve palsy
1st webspace
Guttering between metacarpals
Hypothenar wasting
Describe ulnar claw hand
Significant nerve compression
Hyperextension at NCPJ and flexion at IPJs
What is ulnar paradox?
A distal lesion has worse clawing than proximal lesion, due to intact long flexors with distal lesion
Describe the Froment’s test
Key muscles - adductor pollicis (ulnar nerve) and flexor pollicis longus (median nerve)
If ulnar nerve not working then patient will cheat and use FPL instead of adductor pollicis (thumb flexed)
Describe the lateral femoral cutaneous nerve
Roots are L2 and 3
Lies on surface of iliacus muscles and exits pelvis under lateral end of inguinal ligament
Purely sensory to lateral aspect of thigh
What does compression of lateral femoral cutaneous nerve cause?
Meralgia paraesthetica
What is the treatment of Meralgia paraesthetica?
Common in pregnancy so after will resolve
Injecting tunnel with steroids under US to settle swelling
Then surgery to release tunnel
What is the treatment for cubital tunnel syndrome?
Steroid injection
More often tunnel is released during surgery
Describe the sciatic nerve
Root L4-S3
Largest nerve in body, main branch of sacral plexus and flat with accompanying artery
Exits pelvis through sciatic foremen below piriformis muscle
Runs deep to gluteus maximus muscles
Where does the sciatic nerve supply?
hamstring muscles in thigh (posterior) and part of adductor magnus, and all lower leg and foot muscles via terminal branches
When is sciatic nerve at risk of injury?
Posterior dislocation of hip, intra-muscular injection and during surgery (division devastating)
Describe the common fibular nerve
Roots - L4-S2
Smaller and lateral branch of the sciatic nerve
Enters foot as winds round fibula neck and splits into superficial and deep peroneal nerve
What does injury to common fibular nerve cause?
Foot drop and slapping gait (leg needs lifted higher)
At risk when passes around lateral neck of fibula
